reproduction Flashcards
(139 cards)
1
Q
what are the functions of the male reproductive system
A
production of sperm cells
production of male sex hormones
sustaining and transfer of sperm cells into female
2
Q
what are primary sex organs (in males)
A
gonads - site of gamete and hormone production
testes in males
3
Q
what are secondary sex organs (in males)
A
structures essential in caring for and transporting sperm cells
ducts, accessory sex organs, penis in males
4
Q
where is the scrotum located
A
extends from the body behind the penis
5
Q
describe the structure of the scrotum
A
sac like > divided into two compartments (tunica vaginalis and tunica albuginea)
thin layer of smooth muscle within the dermis (dartos)
skeletal muscle under the dermis (cremaster)
rich blood and nerve supply
6
Q
what are the functions of the scrotum
A
support and protect testes
help regulate temp of testes to maintain at around 35 degrees Celsius
7
Q
where are the testes located
A
within the scrotum
8
Q
describe the structure of the testes
A
oval shaped
~ 4-5 cm
each testis divided into 300-400 compartments called lobules
each lobule contains a long tube called a seminiferous tubule (where sperm is produced)
9
Q
what are the functions of testes
A
production of sperm cells and sex hormones
10
Q
why are the testes located externally to the body if it is such a vital organ
A
assists with strict temperature regulation of around 35 degrees
core temperature (37 degrees) is bad as it negatively impacts spermatogenesis and metabolism and increases the risk of testicular cancer
11
Q
how is the temperature of testes maintained
A
located outside body - temp receptors and sweat glands in scrotum
cremaster muscle - contracts in the cold to bring testes closer to warm pelvis and relaxes in heat to bring testes away from warm pelvis
dartos muscle - contracts in the cold to increase wrinkles which decreases surface area for heat loss and vice versa in the heat
counter current heat exchange - network of testicular veins (pampiniform plexus) around tesituclar artery > heat transfer away from arterial blood to venous blood > maintains a cooler temperature in blood going to testes
12
Q
what is the tunica vaginalis
A
a chamber of the scrotum that is lined by serous membrane to reduce friction
13
Q
what is the tunica albuginea
A
a chamber in the scrotum that is deep to the tunica vaginalis and is a dense CT capsule
14
Q
what are seminiferous tubules
A
highly coiled tubule in each lobule of testes
contains spermatogenic cells and sertoli cells
15
Q
what are in-between the seminiferous tubules
A
blood vessels and leydig cells (make androgens ie testosterone)
16
Q
what are sertoli cells
A
cells that extend from the basement membrane to the lumen of the seminiferous tubule and has tight junctions connecting adjacent cells to form the blood testis barrier
17
Q
what is the function of the blood testis barrier
A
isolates spermatogenic cells from blood because the immune system recognises sperm foreign so the barrier prevents a self immune response
18
Q
what are the functions of sertoli cells
A
control release and mvmt of sperm cells
nourish sperm cells
prevent self immune reaction (blood testis barrier)
secrete inhibin to slow down sperm production
19
Q
what is spermatogenesis
A
process of production of sperm
begins in outermost layer of seminiferous tubule (basement membrane) and proceeds towards lumen
20
Q
what are the three elements of spermatogenesis
A
mitotic proliferation
meiotic division
spermiogenesis
21
Q
outline the process of spermatogenesis
A
- spermatogonia divide into more spermatogonia via mitosis
- spermatogonium moves away from basement membrane to form primary spermatocyte
- primary spermatocyte undergoes meiosis 1 to form secondary spermatocyte
- secondary spermatocyte undergoes meiosis 2 to form spermatid
- spermatid undergoes spermiogenesis to form sperm
22
Q
what is spermiogenesis
A
final stage of spermatogenesis where the round spermatid turns into an elongated spermatozoa so that it is adapted for reaching and penetrating an oocyte
23
Q
what are the 4 key stages of spermiogenesis
A
- development of acrosome - contains digestive enzymes to help penetrate oocyte
- development of flagellum - motility
- condensation of nucleus - protects DNA
- shedding of excess cytoplasm by sertoli cells - streamlined sperm for better motility
24
Q
what are the three main parts of the sperm structure
A
head - contains compact nucleus covered by acrosome which has digestive enzymes for penetration of oocyte
mid-piece - connects head to the flagellum / has mitochondria to power motility
flagellum - tail used for motility
25
what are ducts in the testes responsible for
functional maturation, nourishment, storage and transport of sperm
26
what are the 5 main ducts involved w the testes
seminiferous tubules
rete testis - carry sperm from testes to efferent ducts
efferent ducts - connect rete testis to epididymis
epididymus
ductus (vas) deferens
27
describe the epididymus
posterior side of testis
7m long tubule
3 segments - head, body, tail
28
what are the 5 functions of the epididymus
monitors and adjusts composition of fluid produced by seminiferous tubules
recycle damaged sperm
stores and protects sperm
concentrates sperm
site of functional maturation of sperm
29
how does functional maturation of sperm occur
epididymus secretes a variety of proteins that bind to sperm > stabilise it so it can withstand force during ejaculation and trigger the flagellum to begin moving
dependent on androgens
30
describe the movement of sperm through the ductus deferens
tail of epididymus > ascends posterior side of testis > joins spermatic cord > ascends through inguinal canal into abdominal cavity > passes along later surface of bladder > approaches superior and posterior prostate gland > end enlarges to form ampulla of vas deferens > ejaculatory duct > seminal vesicle gland
31
what are the three parts of the urethra
prostatic - passes through prostate
membranous - through floor of pelvis, surrounded by EUS
spongy - through penis
32
what are the accessory glands
seminal vesicles
prostate gland
bulbourethral glands
33
what are seminal vesicles
paired pouch like glands attached to vas deferens near the base of the urinary bladder that secretes 60-70% of volume of semen
secretes alkaline fluid > neutralise acidic environment
34
what is the prostate gland
single donut shaped gland inferior to the bladder and surrounding the urethra that secretes a milky prostatic fluid that contributes 20-30% of the volume of semen
composed of a cluster of glands, each of which connect to prostatic ducts
35
what are bulbourethral glands
paired pea sized glands located at the base of the penis and connected to urethra which secretes a small amount of alkaline mucus into the urethra prior to ejaculation
36
what is semen
seminal fluid from accessory glands + sperm from testes = semen
sperm ~10% and seminal fluid ~90%
37
what are the key components of seminal vesicles
fructose - metabolised by sperm
prostaglandins - stimulate smooth muscle contractions
fibrinogen - coagulate semen > protect from acidic environments
38
what are the key substances of semen secreted by prostate gland
citric acid - ATP
proteolytic enzymes e.g fibrinolysin- break down clotting proteins > coagulate
seminalplasmin - antibiotic that prevents bacterial infections
39
Describe the structure of the penis
Root - internal in the body
Body - elongated / 3 cylindrical columns of erectile tissue > two large corpora cavernosa on the sides of penis and a single corpus spongiosum on the underside of the penis that surrounds urethra
Glans - end of penis that has high concentration of nerve endings / normally covered by foreskin
40
What are the functions of the penis
Deliver semen to the female during sexual intercourse
Transport urine out of the body
41
Outline how an erection occurs
1. sexual stimulation
2. Parasympathetic neurons release NO > dilation of arteries > increase blood flow
3. Increase pressure in arterial blood > compress veins > reduced venous return
4. Blood accumulates in vascular spaces within erectile tissue of penis
5. Following orgasm > sympathetic nerves contract central artery and smooth muscle around erectile tissue > expels blood out of penis
42
Describe the production of testosterone
Produced by leydig cells in the testes
Increased during puberty > characteristic physical changes and initiate spermatogenesis
43
What are the functions of testosterone
Initiate and maintain spermatogenesis within the testes
Development of male secondary sexual characteristics and for maintaining sex drive
44
Outline the regulation of testosterone production
1. hypothalamus initiates spermatogenesis by secreting GnRH which stimulates secretion of FSH and LH by anterior pituitary
2. LH stimulate leydig cells > testosterone / FHS stimulate sertoli cells > androgen-binding protein > binds to androgen hormones e.g testosterone > become concentrated in seminiferous tubule > ensures testosterone levels remain high in testes
3. Increased testosterone > initiate spermatogenesis but it also has negative feedback on GnRH production
4. Sertoli cells respond to increase sperm levels by secreting inhibin > inhibits FSH secretion > negative feedback on cycle
5. Circulating testosterone levels stimulate sex drive and develop secondary sexual characteristics
45
What is cryptorchidism
Failure of one or both testes to descend into scrotum > sterility due to higher temperatures in the pelvic cavity / increased risk of testicular cancer
46
What is erectile dysfunction
Consistent inability of an adult male to ejaculate or attain or hold an erection long enough for sexual intercourse
Often caused by insufficient release of NO
47
what are the functions of the female reproductive system
production of oocytes in the ovaries
production of female sex hormones (estrogen and progesterone)
reception of spermatozoa
nurturing the development of a new individual
48
what are the primary sex organs in the female reproductive system
gonads - ovaries
49
what are the secondary sex organs in the female reproductive system
uterine tubes, uterus, vagina, mammary glands
50
where are the ovaries located
upper pelvic cavity on the lateral sides of the uterus
51
what are the two ligaments supporting the position of the ovaries
suspensory ligament (contains ovarian vein and ovarian artery)
ovarian ligament
52
describe the structure of the ovaries
denser outer part known as cortex - contains ovarian follicles
inner looser part known as medulla - contains blood vessels and nerves
endocrine and exocrine gland
53
what are the functions of the ovaries
production of oocytes
production of female sex hormones
54
what is an ovarian follicle
oocyte surrounded by supporting granulosa cells
55
what are primordial follicles
primary oocyte + single layer of flat follicle cells
56
what are the two phases of the ovarian cycle
pre-ovulatory (follicular) phase - all events prior to ovulation
post-ovulatory (luteal) phase - all events after ovulation
57
what are the two inter-related processes occurring in the ovarian cycle
oogenesis
folliculogenesis
58
what is a primary follicle
primary oocyte + 1-2 layers of cuboidal follicle cells
59
what is a secondary follicle
enlarged oocyte
additional layers of follicle cells
multiple, small fluid-filled spaces develop between follicle cells
60
what are tertiary follicles
mature (Graafin) follicle
single, large fluid-filled space (antrum)
oocyte surrounded by specialised follicular cells called granulosa cells
61
follicle cells secrete what
estrogen
62
what is ovulation
release of oocyte from ovary
granulosa cells stay w released oocyte
oocyte enters uterine tube
63
what is the corpus luteum
glandular structure left behind in ovary after ovulation
empty tertiary follicle collapses
remaining follicular cells proliferate to fill space
64
corpus luteum secretes what
estrogen AND progesterone
65
what is corpus albicans
if fertilisation doesn't occur, corpus luteum degenerates into corpus albicans
composed of scar tissue
66
what is folliculogenesis
development of follicle
67
what is oogenesis
formation of oocytes
68
outline the process of oogenesis
1. oogonium undergoes mitosis to form millions more oogonium in ovaries (this process stops before birth)
2. oogonium forms a primary oocyte (before birth)
3. primary oocyte undergoes meiosis 1 when puberty begins to form secondary oocytes and polar bodies
4. secondary oocyte undergoes meiosis 2 when fertilisation occurs
5. secondary oocyte becomes a zygotes
69
where are the uterine tubes located
connected to uterus and lies close to (but not connected to) ovary
70
what are the 3 segments of the uterine tubes
infundibulum - has fimbriae which collect ovulated oocyte
ampulla - site of fertilisation
isthmus - site of sperm maturation
71
what are the walls of the uterine tubes comprised of
ciliated columnar epithelium w mucous-secreting cells
72
what is the function of the uterine tubes
transport oocytes from ovaries to the uterus
site of fertilisation (ampulla)
site of sperm maturation (isthmus)
73
where is the uterus located
near the floor of the pelvic cavity anterior to the rectum and posterosuperior to the bladder
74
what are the 3 regions of the uterus
fundus
body
cervix
75
what are the 3 layers of the uterus wall
endometrium - innermost layer, highly vascularised / two layers (stratum functionalis and stratum basalis)
myometrium - thick layer of smooth muscle (contract during childbirth in response to oxytocin)
perimetrium - external layer composed of epithelium
76
what are the functions of the uterus
provides mechanical protection, nutritional support and waste removal for developing embryo
contractions in muscular wall allows for ejection of foetus at birth
77
describe the stratum functionalis
functional layer
grows during uterine cycle
sheds at menstruation
78
describe the stratum basalis
basal layer
denser CT
permanent, does not shed
gives rise to new functionalis
79
describe the cervix
contain mucous glands
mucous consistency varies during cycle (less viscous at ovulation to allow sperm passage)
80
what are the 4 phases of the female reproductive cycle
menstrual phase (days 1-5)
follicular phase (estrogen from follicle cells)
ovulation
luteal phase (estrogen and progesterone from corpus luteum)
81
where is the vagina located
extends from exterior of body to the uterine cervix
82
describe the structure of the vagina
internal wall - stratified swamis epithelium that forms protective surface barrier
beneath this layer is a thin layer of CT containing vaginal glands that secrete lubricating mucous
beneath CT layer is a thick layer of smooth muscle
83
what are the functions of the vagina
serves as a passageway for elimination of menstrual fluids
receives the penis during sexual intercourse and holds sperm prior to their passage into the uterus
forms the inferior portion of the birth canal through which the foetus passes during delivery
84
what are the external female genitalia
vestibule
labia minora
clitoris
prepuce
labia majora
bartholin's glands
85
what is the vestibule
space into which vagina and urethra open
86
what is the labia minora
small thin fold of skin that border the vestibule
87
what is the clitoris
small rounded tissue project that contains two erectile structures called corpus cavernosa
88
what is the prepuce
extensions of the labia minora that encircle the clitoris
89
what is the labia majora
prominent skin folds that encircle and partially conceal the labia minora
90
what are bartholin's glands
secrete lubricating mucus into the vestibule
91
what 3 things are involved in the ovarian cycle of the female reproductive cycle
follicular phase
ovulation
luteal phase
92
what 3 things are involved in the uterine cycle of the female reproductive cycle
menstrual phase
proliferative phase
secretory phase
93
what happens during the pre ovulation phase
GnRH > FSH > development of follicles > secrete estrogen which thicken the stratum functionalis
94
what happens during ovulation
LH surge triggers ovulation
95
what happens during the post ovulatory phase
corpus luteum forms which secretes oestrogen and progesterone, but the negative feedback of the production of these hormones is suppressed for ~ 10 days
96
what happens during the menstrual phase
negative feedback of GnRH begins after ~ 10 days > no oestrogen or progesterone > formation of corpus albicans as spiral arteries constrict > menstruation
97
how does the contraceptive pill work
contains oestrogen and progesterone > triggers negative feedback > decrease GnRH > no FSH and LH > decrease growth of follicles > no ovulation > decrease chance of pregnancy
98
what happens if fertilisation and implantation occurs
embryo secretes hCG hormone which mimics LH, which keeps corpus luteum alive until placenta develops > secretion of progesterone and estrogen so that menstruation doesnt occur
99
what are ovarian cysts
fluid filled sac in or on the ovary - usually non cancerous
cancerous cysts - more likely in women >40
can cause pain, pressure, dull ache, feeling of fullness in the abdomen, pain during sex, vaginal bleeding
usually require no treatment but cysts more than 5cm may need surgery
100
what is endometriosis
characterised by growth of endometrial tissue outside the uterus > enters the pelvic cavity (ovaries, outer surface of uterus, sigmoid colon, cervix, abdominal wall, bladder) > breaks down and bleeds > inflammation, pain and scarring
101
Why are hundreds of millions of sperm released into the vagina
Many of the sperm die due to the acidic nature of the vagina
102
What makes passage of sperm easier in the cervix
If the cervical mucous is watery (pre ovulation)
103
What in the uterus aids the movement of sperm away from the cervix and towards the uterine tubes
Uterine myometrium
104
What happens to sperm in the uterine tubes
Sperm’s flagella becomes hyperactive to generate enough force to push through protective layers around oocyte
Plasma membrane above the sperm’s acrosome thins so that it permits the release of acrosomal enzymes
105
Outline the process of fertilisation
1. Hundreds of sperm attracted to corona radiata > begin breaking through barrier of granulosa cells
2. Contact w zona pellucidia triggers acrosome reaction > secrete digestive enzymes that breakdown glycoprotein membrane of zona pellucia and help expose oocyte’s plasma membrane
3. Single sperm succeeds in burrowing through corona radiata and zona pellucida and making contact w oocyte’s plasma membrane > sperm’s plasma membrane fuses w oocyte plasma membrane > sperm releases nucleus into cytoplasm of oocyte
106
Describe IVF
used when woman may have blocked or compromised uterine tubes
Used when man may have low sperm count or abnormal or immotile sperm
Involves mixing sperm and oocytes together in a Petri dish, then transferring zygotes into the uterus
Rate of success of IVF correlated w a woman’s age
107
what are the 3 parts of the prenatal period and length of each
fertilisation - 2nd week
embryonic period - 2nd-8th week
fetal period - 8th week to birth
108
what is clinical age
using the date of mother's last period to calculate the unborn child's age
109
what is developmental age
unborn child's age from fertilisation
14 days less than clinical age as fertilisation occurs ~14 days after last period
110
outline preimplantation development
day 0 - zygote forms as fertilisation is complete
day 1-3 - zygote undergoes mitosis (cleavage) making the zygote go from 2 cell to 4 cell to 8 cell and so on
day 4 - morula (solid ball of cells) form > begins to descend towards uterus from oviduct
day 5 - morula continues to proliferate and differentiate into blastocyst
day 6-7 - trophoblast cells release enzyme > break down zona pellucida > blastocyst contacts and adheres to uterine lining
111
outline implantation
day 8
trophoblast cells divide into several layers
cells near endometrial wall (synctiotrophoblast) develops into cords that hold onto endometrium
inner and outer layer of trophoblast cells form chorion > secrete hCG
112
what is human chorionic gonadotropin
hCG
transported in bloodstream from uterus to ovary
in ovary, it directs corpus luteum to remain alive and continue secreting estrogen and progesterone which prevents menstruation
levels peak around 8-9weeks after fertilisation and then declines after this as placenta secretes estrogen and progesterone to prevent menstruation
113
what is the epiblast
upper layer of embryonic disc that will become embryo layers
114
what is the hypoblast
lower layer of embryonic disc that will become extra embryonic tissue including yolk sac
115
what is the primitive streak
midline region of the embryonic disk thickens in early week 3
beginning of gastrulation
116
what is gastrulation
epiblast cells migrate through the primitive streak to become 3 germ layers
early migrating cells displace hypoblast cells to form embryonic endotherm
later migrating cells form the mesoderm
this embryonic development progresses from the cranial end, later caudal
117
what are the 3 germ layers
ectoderm
mesoderm
endoderm
118
what does the ectoderm produce
skin, nervous system, skull, enamel, inner ear, adrenal medulla, eye, ear
119
what does the mesoderm produce
muscle, some viscera, bones, blood, lymph
120
what does the endoderm produce
epithelial lining of ducts and organs, some viscera, primordial germ cells
121
outline development of the neural tube
mesoderm cells develop into notochord which induces the overlying ectoderm to form the neural plate > gives rise to CNS
groove in the neural plate at day 18 > become larger > fuse > produce neural tube
122
outline the development of neural crest cells
develop from neuroectodermal cells along inner margins of neural tube
will later produce ganglia in spine and ANS
123
what are teratogens
factors that cause birth defects
e.g alcohol, thalidomide, maternal-fetal infections
124
what are NTDs
neural tube defects
occurs due to the failure of fusion of grooves in the neural plate which from neural tubes
125
What are the major functions of the placenta
Nutrient, gas, waste exchange
Hormone production
Protection from environment
Immune protection
126
What are the important placental hormones
Human chorionic gonadotropin
Progesterone and estrogen
Placental lactogen and GH
Relaxin
127
What is the function of progesterone made by the placenta
Relaxes uterine muscle to prevent labour
Induces breast changes in preparation for lactation
128
What are the functions of placental lactogen and GH
Induce maternal metabolic changes e.g insulin resistance > maintains maternal placental glucose concentration to compensate for placental uptake
Promote breast changes in prep for lactation
129
What are the functions of relaxin released by the placenta
Vascular - vasodilation and decreased myogenic tone
Cardiac - increase Q and increase SV
Renal - increase GFR
Joints and cartilage - increase flexibility + cervical softening
130
How does the placenta act to protect the fetus from the external environment
Barrier to many bacteria but many viruses can still cross the placenta
Drug and hormone metabolism and clearance e.g deactivation of cortisol to cortisone
Does not block alcohol tho as it can diffuse across membrane
131
How does the placenta aid immunity
IgG antibodies are transferred across the human placenta (esp in late preggo) > maternal immunisation can protect newborn against disease
132
Outline increased beta cell mass during pregnancy
Happens in early pregnancy
Increased insulin secretion > promotes fat storage
133
Outline altered glucose metabolism in late pregnancy
Adaptations maintain maternal circulating glucose to maintain fetal supply > increase insulin but decrease insulin sensitivity and increase basal hepatic glucose production via gluconeogenesis
134
Outline lipid metabolism during pregnancy
Decrease in the first 8 weeks and then increase
Late preg > increase insulin resistance > increase lipolysis > increase circulating FA and glycerol for maternal and placental energy supply
Shift to fat oxidation as maternal energy source
Increase cholesterol > placental steroid synthesis
Fasting > increase fat oxidation > ketones for fetal energy
135
What are the cardiovascular adaptations during pregnancy
Increase HR, increase SV, increase Q
Decrease BP first half of pregnancy
Increased blood volume
136
Why is there an increase in cardiac function during pregnancy
Q increased bc blood volume increases
Progesterone may stimulate maternal heart growth
Elevated estrogen in late pregnancy may allow increased activation of stretch activated kinases to further stimulate heart growth
137
Why does BP fall in the first half of pregnancy
Vascular resistance decrease + arterial compliance increase > increase blood vessel volume and decrease after load on heart
Vasodilation and arterial compliance due to increase NO production (elevated maternal relaxin and estrogen)
138
Why is there an increase in blood volume during pregnancy
Elevated aldosterone and cortisol (esp late pregnancy) > sodium and water retention > increase fluid volume
RAAS upregulated by estrogen (esp late preg) > increase sodium absorption
Osmostat set point changes so that thirst increases at lower than usual osmolality
139
Are there clinical consequences to increased fluid volumes during pregnancy
Development of oedema
Increase CT fluid can also increase laxity and pain of some joints
